Haecceities are non-qualitative properties for individuation but the current theories about haecceities are still to be much more explored. This paper aims to develop a “haecceity mereology” – that is, an ontological system that understands substances as mereological combinations of haecceities and qualitative properties. In this way, the view developed is an alternative to Paul’s : 578–96; 2006. “Coincidence as Overlap.” Noûs 40 : 623–59) mereological approach. Three rules are proposed: If S is a substance, then there is one and (...) only one haecceity which is S’s qualitative part; For all the fusions with the same haecceity, at most only one of those fusions is a substance; When all the relevant elements are abundant, every element must overlap at least one substance. This is the first ontology of haecceities in the recent literature and would be a model for systematic metaphysics. (shrink)

Among modal claims, claims that involve the notions of broadly logical possibility and necessity, one that seems almost trivial is this: that if some proposition is possible, then it is possibly true. However, there is an argument, due in its essentials to the medieval philosopher and logician Jean Buridan, to the effect that this seemingly trivial claim is, in fact, untrue. ;Briefly put, the argument is this. Let Q be the proposition that Quine does not exist. Since Quine's existence is (...) contingent, Q is possible. But, propositions are ontologically dependent upon their constituents, and Quine is a constituent of Q. So, necessarily, were Quine not to exist, neither would Q exist. And, a necessary condition of a proposition's being true is that it exist. Hence, there are propositions, such as Q, that are possible, but not possibly true. I call this conclusion, together with certain other similar claims, 'Buridanism'. ;My main topic is the evaluation of the argument for Buridanism, and the exploration of the consequences of Buridanism for modalist theories of possible worlds and for modal logic. I begin by examining the two crucial premises in the argument for Buridanism: N-dependency, according to which propositions expressed by sentences containing proper names are singular propositions that depend ontologically upon the referents of those names, and Buridan's Thesis, according to which a proposition can be neither necessary, nor possible, nor true, unless it exists. ;Robert Adams has argued that accepting Buridanism forces us to revise the modalist conception of possible worlds as maximal and consistent propositions or sets of propositions. I show that this is not the case, and provide an analysis of a proposition's being true relative to a world that allows us to maintain the modalist account while embracing Buridanism. ;Standard systems of quantified modal logic are prone to several related problems that I refer to as the problems of contingency. These systems often include as theorems formulas that seem to presuppose that everything that exists, exists necessarily. I develop a system of modal logic, BML, based upon Buridanism, that is able to overcome these difficulties. (shrink)